International Questionnaire Postal Response Rate: An experiment comparing no return postage to provision of International Postage Vouchers – "Coupon-Réponse International"

BACKGROUND Previous studies of methods to increase response rates on international postal surveys did not include providing return postage. We provided International Postage Vouchers--"Coupon-Réponse International" to cover this. The objective of this study was to see if these International Postage Vouchers had an effect on response rates. METHODS Between-groups, randomized, after-only. RESULTS There was no difference in response rates between the group that received International Postage Vouchers and the group that did not. (p = 0.23). CONCLUSION International Postage Vouchers--"Coupon-Réponse International" have no effect on response rates for international postal surveys.